Abstract
The structural gene coding for ADP-glucose pyrophosphorylase (AGPase) in the cyanobacterium, Synechococcus elongatus PCC 7942 was disrupted by the insertion of blasticidin S resistant gene. The growth rate of the AGPase mutant in liquid culture medium was considerably lower compared to that of the wild type. The enzymatic activity of AGPase in the crude extract of the mutant was below undetectable level. Glycogen synthase activity was also decreased to 1/5 of that in the wild type. Accumulation of glycogen was completely abolished in the AGPase mutant. In the presence of 0.2 M NaCl, sucrose was synthesized in S. elongatus PCC 7942. The rate of sucrose accumulation was slower in the AGPase mutant and the sucrose content attained in the mutant was 1/2 of that in the wild type. The physiological characteristics of the AGPase mutant were examined in comparison to those of the glycogen synthase mutant that we isolated previously.
